2.3. Measures

The main outcome measures of our study were the prevalence, deaths, YLLs, YLDs, and DALYs associated with maternal disorders. The prevalence of a condition refers to the proportion of the population that has that condition at a specific time. YLDs refer to years of life lived with any sort of health-related disability over time and are calculated as the product of the disability weight and the prevalence number. (The disability weight is a value between 0 and 1 that represents the health loss severity related to a particular disease.) The details of the disability weights used in the GBD 2019 were reported elsewhere [5]_.

The YLLs were computed by multiplying the number of deaths from each cause in each age group by the reference life expectancy at the average age of death among those who died in the age group [7]. DALYs are commonly used to measure the overall disease burden and are expressed as the sum of YLLs due to premature death and YLDs [8].

For our metrics, we extracted YLD data in terms of the prevalence (YLD counts), rate (per 100,000 people), and percentage (proportion of YLDs due to the selected conditions relative to the total YLDs). For age, we extracted YLD data for all ages and as age-standardized rates. The estimates are reported with 95% uncertainty intervals (UIs) [9]. Thirty-three provinces/regions of China, including 31 mainland provinces, municipalities, and autonomous regions and the Hong Kong and Macao Special Administrative Regions, were analyzed.